The U.S. Postal Service is placing its landmark Greenwich Avenue building up for sale, planning to relocate the branch to a smaller outlet nearby.

Maureen Marion, a Postal Service spokeswoman for Connecticut, said the 17,000-square-foot facility at 310 Greenwich Ave. -- built as a post office in 1917 and listed on the National Register of Historic Places -- is too big for the current retail operation, which employs four people. Mail sorting is done out of the Postal Service's facility on Valley Drive.

"It's not a space that we have used wisely for a number of years," Marion said.

The plan is to seek a buyer for the building and, once a sale is worked out, look for a new location. Marion said Friday that an asking price was not yet available.

The move comes as the Postal Service has been looking to make cuts across the country -- plans include eliminating Saturday mail delivery and closing post offices -- to deal with a huge revenue shortfall.

Marion said the Postal Service's intention is to keep the branch open until it secures another space.

A central Greenwich outlet with the same operation could work out of a 5,000-square-foot space, Marion said.

"Should we get fortunate enough to be able to sell this building, get a buyer who is committed on paper to the sale, we believe the opportunity in the immediate area to find a location will be good," Marion said. "We already own the property, so it's not as though we have a requirement to leave, but if we can do this, we certainly need to explore the possibility. ... It is an option we believe bodes well for both the customers and the community."

Postal Service officials informed the town of its plan this week.

"I certainly consider the building to be a landmark for our town," Greenwich Frist Selectman Peter Tesei said. "It has a tremendous value to the community, particularly to residents who have been here for many, many years. ... I'm disappointed and saddened to see that decision has to be made, but certainly understand and respect it from a business point of view."

Tesei said the Postal Service will work with the town to schedule a public meeting, where they would likely seek input on a new location.

The war memorial located in the small plaza outside the post office is owned by the town and will not be affected by the sale, Tesei said. Because of the building's historic value, any buyer's plans would undergo scrutiny by the Planning and Zoning Commission.

As a constant trickle of customers went through the post office Friday afternoon, some said they were saddened to learn of the sale, noting that the location was convenient for employees of the nearby retail stores.

"It's certainly a landmark on the Avenue," said lifelong Greenwich resident Shannon Kennedy, 50, who runs a security guard firm started by her father on East Elm Street. "It adds to the flavor of the whole town and the history."

As he stopped off to mail his tax forms to the state, Jeffrey Howard said there may be one advantage to a new post office location.

"I hope maybe the new location would have more parking," said Howard, who has lived in Greenwich since 1977. "That'd be the only advantage in them moving. Otherwise, I feel badly about it."

Staff writer Lisa Chamoff can be reached at lisa.chamoff@scni.com or 203-625-4439.